简介：One-dimensionalorderedwatermoleculesenteringandexitingfromacarbonnanotubewithanappropriateradiusarestudiedwithmoleculardynamicssimulations.Itcanbefoundthatawatermoleculenearthenanotubeendismorelikelytobeexpelledfromthenanotubeifitsdipoleisalmostperpendiculartothenanotubeaxis.ThekeytothisobservationisthatthosewatermoleculesareclosertothewallofthenanotubeawayfromtheequilibriumpositionoftheLennar-Jones(LJ)potential.Thus,theinteractionenergyforthosewatermoleculesisrelativelyhigh.Therearetwoparticularstructuresoftheperpendicularwatermoleculedependingonthedipoledirectionoftheadjacentwatermoleculeinthenanotube.Althoughtheprobabilitiesofthesestructuresarequitesmall,theircontributionstothenetfluxacrossthenanotubeendareapproximatelyequaltothepredominantstructures.Thepresentfindingsfurthershowthepossibilityofcontrollingthewaterflowbyregulatingthedipoledirectionsofthewatermoleculesinsidethenanochannels.

简介：InthispaperweextendthemethoddevelopedinforlimitingStokeswaveofinfinitewaterdepthtocoverthecaseoffinitedepth.Themethodhashighefficiencyandtheresultisaccurate.

简介：Evaporationofsessilewaterdropletonpolydimethylsiloxane(PDMS)surfaceswiththreedi?erentcuringratios(5:1,10:1,and20:1)wasexperimentallyinvestigatedinthispaper.Weshowthattheconstantcontactradius(CCR)evaporationonsurfacewithhighcuringratiolastslongerthanthatwithlowcuringratio.WealsomeasuredYoung’smoduliofPDMSfilmsbyusingatomicforcemicroscopy(AFM)andsimulatedsurfacedeformationofPDMSfilmsinducedbysessilewaterdroplet.WithincreasingcuringratioofPDMSfilm,Young’smodulusofPDMSfilmisgettinglower,andthentherewillbelargersurfacedeformationandmoreelasticstoredenergy.Sincesuchenergyactsasabarriertokeepthethree-phasecontactlinepinned,thusitwillresultinlongerCCRevaporationonPDMSsurfacewithhighercuringratio.

简介：Thispaperinvestigatesthestabilityofnitrogennanobubblesunderdifferentconcentrationsofnitrogenmoleculesbymoleculardynamicssimulations.Itisfoundthatthestabilityofnanobubblesisverysensitivetotheconcentrationofnitrogenmoleculesinwater.Asharptransitionbetweendispersestatesandassemblestatesofnitrogenmoleculesisobservedwhentheconcentrationofnitrogenmoleculesischanged.Therelevantcriticalconcentrationofnitrogenmoleculesneededbytheexistingnitrogennanobubblesisanalyzed.

简介：Thisworkfocusesonthestudyoftheeffectofhydrophobicityonthewaterflowincarbonnanotubes(CNTs)usingamoleculardynamics(MD)approachforawiderangeofpotentialapplicationssuchaswaterpurificationandhighefficiencyofnanofluidenergyabsorptionsystems(NEAS).ThehydrophobicitybetweenliquidwaterandsurfaceofCNTswascharacterizedbyinteraction-energy-coefficient(IEC)—aparameterdescribingtheenergyinteractionstrengthbetweenwatermoleculesandcarbonatoms.Itisshownthatthestaticcontactanglesbetweenwaterandcarbonsurfacedecreasefrom155°to44°whenthevaluesofIECincreasefrom0.042kJ/molto2.196kJ/mol.Inaddition,thepressuredropsinCNTbecameindependentofIECwhentheIECvaluewashigherthan1.192kJ/molforagivenflowrate.ItwasfoundthatthehydrophobicityofCNTsurfacehasasignificantimpactonthepressuredropofwaterflowintheCNTsandMDmethodprovidesaquantitativeevaluationoftheimpact.

简介：Thestudyofbed-loadtransportisofgreatsignificancebothintheoryandinpractice.Thispaperdiscussesthesaltationofbed-loadsolidgrainsinflowingwater.Experimentsandtheoreticanalysishavebeenmadebymeansofhigh-speedphotographingandadvanceddataprocessingtechniquewithacombinedmethodbasedonmechanicalandstatisticaltheories.Itindicatesthatthesaltationisthemainformofthebed-loadtransportunderordinaryflowingconditions.Inthemeantime,takingsuecessivesaltationasthemod-elofbed-loadtransport,systematicanalysishasbeenmadewithregardtothekinematicpropertiesandmechanismofsaltation.ThestatisticalanalysisshowsthattheprobabilitydensityfunctionsoftherelativeheightandlengthofsaltationareinconformitywithΓ-typedistribution,whiletheprobabilitydensityfunc-tionsoftherelativevelocitiesofsaltationareinconformitywiththeGaussiandistribution.

简介：Byusingthematchedasymptoticexpansionmethodandtheideaofedgelayer,amathematicmodelfordescribingtheinteractionbetweenweaklynonlinearshallow-waterwavesandthree-dimensionalfloatingbodiesisformedinthepaper.Asanumericalexample,thediffractionofasolitarywavearoundaverticallyfloatingcir-cularcylinderhasbeeninvestigatedandtheresultsarepresented.Thepresentmethodcanfurtherbeextendedtothestudyofwavediffractionaroundfloatingbodiesofgeneralshape.

简介：Basedonthefundamentaldynamicequationsoffunctionallygradedmaterial(FGM)cylindricalshell,thispaperinvestigatesthesoundradiationofvibrationalFGMshellinwaterbymobilitymethod.ThismodeltakesintoaccounttheexteriorfluidloadingduetothesoundpressradiatedbytheFGMshell.TheFGMcylindricalshellwasexcitedbyaharmoniclineradialforceuniformlydistributingalongthegenerator.TheFGMshellequationsofmotion,theHelmholtzequationintheexteriorfluidmediumandth...

简介：Theturbulencestructuresnearashearedair-waterinterfacewereexperimentallyinvestigatedwiththehydrogenbubblevisualizationtechnique.Sur-faceshearwasimposedbyanairflowoverthewaterflowwhichwaskeptfreefromsurfacewaves.Resultsshowthatthewindshearhasthemaininfluenceoncoher-entstructuresunderair-waterinterfaces.Low-andhigh-speedstreaksformintheregionclosetotheinterfaceasaresultoftheimposedshearstress.Whenacertainairflowvelocityisreached,'turbulentspots'appearrandomlyatlow-speedstreakswithsomecharacteristicsofhairpinvortices.Atevenhighershearrates,theflowneartheinterfaceisdominatedprimarilybyintermittentburstingevents.Thecoher-entstructuresobservednearshearedair-waterinterfacesshowqualitativesimilaritieswiththoseoccurringinnear-wallturbulence.However,afewdistinctivephenomenawerealsoobserved,includingthefluctuatingthicknessoftheinstantaneousboundarylayerandverticalvorticesinburstingprocesses,whichappeartobeassociatedwiththecharacteristicsofair-waterinterfaces.

简介：ThecaptureoforthophosphatesandtotalphosphorusfromthePudongCanalriverinthePudongDistrictofShanghaibyTiO2nanoparticlesisstudiedusingarotatingphotoreactorandthenano-TiO2photocatalystDegussaP25.TheeffectsofUVirradiationintensityinarangeof20-74mW/cm2.theloadingoftheTiO2nanoparticlesinarangeof0.05-0.1g/L,irradiationtimeupto4h,andpHvaluesinarangeof2-10.5onthecaptureefficiencyareinvestigated.TheresultsshowthatthecaptureoforthophosphatesandtotalParesignificantlyenhancedbyUVirradiation;ataloadingof0.1g/Landanirradiationintensityabove36mW/cm2,orthophosphatesandtotalphosphorusarerapidlycapturedbyTiO2nanoparticles,causinganobservedreductionfrom0.4mg/Ldownto0.02mg/L.pHvaluesinarangeof2-10.5havelittleeffectonthecaptureefficiencyoforthophosphatesandtotalphosphorus.

简介：Wepresentsecond-orderexpressionsforthefree-surfaceelevation,velocitypotentialandpressureresultingfromtheinteractionofsurfacewavesinwaterofarbitrarydepth.Whenthesurfacewaveshavenearlyequalfrequenciesandnearlyoppositedirections,asecond-orderpressurecanbefeltallthewaytotheseabottom.Thereareatleasttwoareasofapplications:reflectivestructuresandmicroseisms.Microseismsgeneratedbywaterwavesintheoceanaresmallvibrationsofthegroundresultingfrompressureoscillationsassociatedwiththecouplingofoceansurfacegravitywavesandtheseafloor.Theyarerecordedonland-basedseismicstationsthroughouttheworldandtheyaredividedintoprimaryandsecondarytypes,asafunctionofspectralcontent.Secondarymicroseismsaregeneratedbytheinteractionofsurfacewaveswithnearlyequalfrequenciesandnearlyoppositedirections.Theefficiencyofmicroseismgenerationthusdependsinpartonoceanwavefrequencyanddirection.Basedonthesecond-orderexpressionsforthedynamicpressure,asimpletheoreticalanalysisthatquantifiesthedegreeofnearnessinamplitude,frequency,andincidenceangle,whichmustbereachedtoobservethephenomenon,ispresented.

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简介：Afiniteelementisestablishedforanalyzingthedynamicalmechanicsanddeformationofsteelframeathightemperaturewhenitisrapidlycooleddownbyspraywaterinfirefighting.Thesimulationresultshowsthatremarkablemechanicalcouplingeffectsareproducedintheprocess,andthesectionalstressinrapidcoolingdownisfoundconsiderablylargerthanthatinheating-up.Meanwhile,thestressanddeformationofabeammainlyrelatedtocoolingrateandlocationaremuchlargerthanthoseofacolumninrapidcooling.Infirefighting,thestructureonthefirstorsecondfloorwasmoredangerousthanthoseonotherfloorsinrapidcooling.Theseresultscouldprovideatheoreticalreferenceforthedesignofsteelstructureandfirefighting.

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简介：ＴＷＯ－ＰＨＡＳＥＦＬＯＷＦＯＲＡＨＯＲＩＺＯＮＴＡＬＷＥＬＬＰＥＮＥＴＲＡＴＩＮＧＡＮＡＴＵＲＡＬＬＹＦＲＡＣＴＵＲＥＤＲＥＳＥＲＶＯＩＲＷＩＴＨＥＤＧＥＷＡＴＥＲＩＮＪＥＣＴＩＯＮＧｕｏＤａｌｉ（郭大立）ＬｉｕＣｉｑｕｎ（刘慈群）（Ｒｅｃｅｉｖｅ...

简介：AvisualizedinvestigationwascarriedoutontheeffectofthedivergingangleonthebubblemotionandinterfacialbehaviorinaVenturi-typebubblegenerator.Itwasfoundtwoorthreelargevortexesformedinthedivergingsection,resultinginstrongreentrantjetflowinthefrontofthebubblesorslugsrushingoutofthethroat.Thejetflowinreturnbumpsintotheongoingbubblesorslugs,leadingtostronginteractionbetweenthegasandliquidphases.Thediverginganglehassignificantinfluenceonthereentrantflowprocessandtheperformanceofthebubblegeneratoraswell.Increasingthedivergingangleresultsinthereentrantflowmovingfurtherforwardtotheupstreamandintensifiestheinteractionbetweenthetwophases.Asaconsequence,thebreakuporcollapseofbubblesbecomesmoreviolent,wherebyfinerbubblesaregenerated.Assuch,thereentrantflowstronglylinkstotheperformanceoftheVenturichanneltakenasabubblegenerator,andthatamoderateincreaseinthediverginganglecanimproveitsperformancewithoutadditionalincreaseinflowresistancelikethatbyincreasingliquidflowrate.

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简介：Aninitial-boundaryvalueproblemforshallowequationsystemconsistingofwaterdynamicsequations,silttransportequation,theequationofbottomtopographychange,andofsomeboundaryandinitialconditionsisstudied,theexistenceofitsgeneralizedsolutionandsemidiscretemixedfiniteelement(MFE)solutionwasdiscussed,andtheerrorestimatesofthesemidiscreteMFEsolutionwasderived.Theerrorestimatesareoptimal.

简介：Basedonthetensoranalysisofwater-sedimenttwo-phaseflow,thebasicmodelequationsforclearwaterflowandsediment-ladenflowarededucedinthegeneralcurvecoordinatesfornaturalwatervariable-densityturbulentflow.Fur-thermore,correspondingboundaryconditionsarealsopresentedinconnectionwiththecompositionandmovementofnon-uniformbedmaterial.Thetheoreticalresultsareappliedtothecalculationofthefloatopencaissonintheconstructionperiodandgoodresultsareobtained.

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